Buggy code:
public class ComplexFieldUtil { public static final String FORWARD_INDEX_ID_BOOKKEEP_NAME = "fiid" ; private static final String CONTENT_ID_BOOKKEEP_NAME = "cid" ; private static final String LENGTH_TOKENS_BOOKKEEP_NAME = "length_tokens" ; private static final String DEFAULT_MAIN_PROP_NAME = "word" ; public static final String SENSITIVE_ALT_NAME = "s" ; private static final String DEFAULT_MAIN_ALT_NAME = ComplexFieldUtil . SENSITIVE_ALT_NAME ; public static final String INSENSITIVE_ALT_NAME = "i" ; public static final String CASE_INSENSITIVE_ALT_NAME = "ci" ; public static final String DIACRITICS_INSENSITIVE_ALT_NAME = "di" ; public static final String START_TAG_PROP_NAME = "starttag" ; public static final String END_TAG_PROP_NAME = "endtag" ; public static final String PUNCTUATION_PROP_NAME = "punct" ; public static final String LEMMA_PROP_NAME = "lemma" ; public static final String PART_OF_SPEECH_PROP_NAME = "pos" ; static String PROP_SEP ; static String ALT_SEP ; static String BOOKKEEPING_SEP ; static int ALT_SEP_LEN ; static int PROP_SEP_LEN ; static int BOOKKEEPING_SEP_LEN ; private static final List < String > BOOKKEEPING_SUBFIELDS = Arrays . asList ( ComplexFieldUtil . CONTENT_ID_BOOKKEEP_NAME , ComplexFieldUtil . FORWARD_INDEX_ID_BOOKKEEP_NAME , ComplexFieldUtil . LENGTH_TOKENS_BOOKKEEP_NAME ) ; public enum BookkeepFieldType { CONTENT_ID , FORWARD_INDEX_ID , LENGTH_TOKENS ; } public static boolean isBookkeepingSubfield ( String bookkeepName ) { } public static ComplexFieldUtil . BookkeepFieldType whichBookkeepingSubfield ( String bookkeepName ) { } public static String contentIdField ( String fieldName ) { } public static String forwardIndexIdField ( String propFieldName ) { } public static String forwardIndexIdField ( IndexStructure structure , String fieldName ) { } public static String lengthTokensField ( String fieldName ) { } public static String startTagPropertyField ( String fieldName ) { } public static String endTagPropertyField ( String fieldName ) { } @ Deprecated public static boolean usingOldFieldNames ( ) { } public static void setFieldNameSeparators ( boolean avoidSpecialChars ) { } @ Deprecated public static void setFieldNameSeparators ( boolean avoidSpecialChars , boolean oldVersion ) { } public static String bookkeepingField ( String fieldName , String propName , String bookkeepName ) { String fieldPropName = "" ; boolean propGiven = ( propName != null ) && ( ( propName . length ( ) ) > 0 ) ; if ( ( fieldName == null ) || ( ( fieldName . length ( ) ) == 0 ) ) { if ( propGiven ) { fieldPropName = propName ; } else <START_BUG> throw new RuntimeException ( "Must<seq2seq4repair_space>specify<seq2seq4repair_space>a<seq2seq4repair_space>base<seq2seq4repair_space>name,<seq2seq4repair_space>a<seq2seq4repair_space>property<seq2seq4repair_space>name<seq2seq4repair_space>or<seq2seq4repair_space>both" ) ; <END_BUG> } else { fieldPropName = fieldName + ( propGiven ? ( ComplexFieldUtil . PROP_SEP ) + propName : "" ) ; } if ( ( bookkeepName == null ) || ( ( bookkeepName . length ( ) ) == 0 ) ) return fieldPropName ; return ( fieldPropName + ( ComplexFieldUtil . BOOKKEEPING_SEP ) ) + bookkeepName ; } public static String bookkeepingField ( String fieldName , String bookkeepName ) { } public static String propertyField ( String fieldName , String propName , String altName ) { } public static String propertyField ( String fieldName , String propName ) { } public static String propertyAlternative ( String fieldPropName , String altName ) { } @ Deprecated public static String fieldName ( String fieldName , String propName ) { } @ Deprecated public static String fieldName ( String fieldName , String propName , String altName ) { } @ Deprecated public static String [ ] split ( String fieldPropAltName ) { } public static String [ ] getNameComponents ( String luceneFieldName ) { } public static String getBaseName ( String luceneFieldName ) { } @ Deprecated public static String getAlternative ( String fieldPropAltName ) { } @ Deprecated public static String getProperty ( String fieldPropAltName ) { } public static boolean isAlternative ( String fieldPropAltName , String altName ) { } @ Deprecated public static boolean isProperty ( String fieldPropAltName , String propName ) { } public static String mainPropertyField ( IndexStructure structure , String fieldName ) { } public static String mainPropertyOffsetsField ( IndexStructure structure , String fieldName ) { } public static String getDefaultMainPropName ( ) { } @ Deprecated public static boolean isMainPropertyNameless ( ) { } public static String getDefaultMainAlternativeName ( ) { } @ Deprecated public static boolean isMainAlternativeNameless ( ) { } public static boolean avoidSpecialCharsInFieldNames ( ) { } public static boolean isCaseSensitive ( String fieldPropAltName ) { } public static boolean isDiacriticsSensitive ( String fieldPropAltName ) { } }

Fix:
throw new RuntimeException ( ( ( ( ( ( "Must<seq2seq4repair_space>specify<seq2seq4repair_space>a<seq2seq4repair_space>base<seq2seq4repair_space>name,<seq2seq4repair_space>a<seq2seq4repair_space>property<seq2seq4repair_space>name<seq2seq4repair_space>or<seq2seq4repair_space>both:<seq2seq4repair_space>" + fieldName ) + ",<seq2seq4repair_space>" ) + propName ) + ",<seq2seq4repair_space>" ) + bookkeepName ) ) ;